Steve
Could this be Eliza and Henry in 1871? The elder children pre-date the marriage date you give. Eliza gives her place of birth as Clerkenwell, and luckily I have the 1851 Clerkenwell index! I will check this if you think that the 71 entry relates to your family.
Rick
1871 Census. RG10/148 Folio 21
Rathbone Place, Marylebone
MANN
Henry, Head, Mar, 28, French Polisher, b Marylebone Middlesex
Eliza, Wife, 27, b Clerkenwell Middlesex
Arthur, Son, 6, Scholar, b St Pancras Middlesex
Elizabeth, Dau, 8, Scholar, b St Pancras Middlesex
Roseanna, Dau, 1, b Marylebone